SINGAPORE - The police said they have contacted Gilbert Goh, founder and president of Transitioning - Unemployment Support Services, regarding his Facebook post that called on members of the public to deface a poster of Prime Minister Lee Hsien Loong during a demonstration planned for May 1.

Mr Goh was advised against carrying out such activities during the demonstration as they may constitute offences under the Penal Code and the Miscellaneous Offences (Public Order and Nuisance) Act, said the police in a statement.

He was also asked to remove any online posting that called for activities which could be deemed illegal.

The police added that Mr Goh is free to hold his planned demonstration at the Speakers' Corner in Hong Lim Park, but it is his responsibility to ensure that the activities conducted there do not contravene the law.

He had suggested in a Facebook post on April 19 that a "huge poster" of PM Lee be put up at the demonstration, for protesters to "vent their anger" upon.

He had invited them to spit, throw eggs and splash dog excrement at the poster.